A great article over at Recoil magazine about the M3A1.
The old Grease Gun was named for its resemblance to the tool still used by mechanics today. Inspired by the British Sten and German MP40, and developed during early WWII, “the Greaser” was made almost entirely of stamped metal with only a couple of machined parts. Production cost was $15 per unit in 1943, equal to about $220 today. The Army touted it as more accurate than the Thompson, claiming a soldier firing an M3 full-auto offhand would keep 90 percent of his rounds inside a 6×6-foot target at 50 yards. We like to call this claim “absolute nonsense;” the Greaser was appreciated for its ability to spray an area with heavy .45 rounds, but nobody ever called it precise.
Nobody ever called it precise, but you could lay down a base of fire with it, and it was fairly easy to hit a half-silhouette at 50 meters.
The M3A1 was my favorite personal firearm during my Army years. It was cheap, clunky, and inaccurate, but it was a helluva lot of fun to shot. There was something cool about spraying .45 ball across the lndscape.